Vital signal sensors employing piezoelectric sheets as sensors have been known. When a pressure generated by a pulse wave, a respiration, or a body motion is applied on the piezoelectric sheet, an electrical signal having a size corresponding to the pressure is generated from the piezoelectric sheet. A vital signal can be detected through the use of this electrical signal.
Patent Literature 1 discloses a piezoelectric sensor including: a piezoelectric body made from a macromolecular material; a first electrode supporting section being disposed on one side of the piezoelectric body and supporting a signal electrode on a first insulator; and a second electrode supporting section being disposed on the other side of the piezoelectric body and supporting a ground electrode on a second insulator. In the piezoelectric sensor, the signal electrode is confined within a region of the piezoelectric body as viewed in a direction in which the piezoelectric body, the first electrode supporting section, and the second electrode supporting section are overlapped with one another, and the entire piezoelectric body is confined within a region of the ground electrode or disposed so as to overlap the region of the ground electrode.